The present invention relates to devices for reading information from information recording disks or devices for writing information onto such disks: e.g., optical disk drives such as CD-ROM drives, CD-R/RW drives, DVD-ROM drives, DVD-RAM drives, DVD-R/RW drives, etc., magneto-optic disk drives such as MO drives, MD drives, etc., and magnetic disk drives such as hard disk drives or the like.
When a CD-ROM drive or the like operates for reproduction, it reads information from a disk mounted on it, while making the disk revolving at the maximum speed (maximum revolutions per second), in order to read necessary information as quickly as possible from the disk. If the disk drive remains inoperative for reading from the disk for a preset period, it sets the disk revolving at low speed. If the disk drive still remains inoperative for reading for a further longer preset period, it stops the disk. By controlling the disk revolution in this way, low power consumption and noise reduction designed for CD-ROM drives or the like are achieved. By way of example, a typical CD-ROM drive structure is represented in a block diagram shown in FIG. 1.
A host computer (the principal unit using the CD-ROM drive) 101 commands the CD-ROM drive (the device for reproducing information from information recording disks) 102 to read information from an information recording disk 103 mounted on it. Directive information required for reading, which comprises, for example, an on-the-disk location in which object data to be retrieved is recorded and length of the object data, can be known from control information. The control information includes, for example, information recorded beginning from 0 minutes, 2 seconds, and 16 frames on the disk in the case of CD-ROMs complying with ISO 9660 and TOC information in the case of CD-DA. Even for other types of disks, the location where object data is recorded and data length can be known from the control information equivalent to the above examples.
From the host computer 101, upon receiving the command to read information, a microprocessor 104 activates a program for information reading from the information recording disk, the program stored in a ROM 105. A specific procedure of the program-controlled microprocessor operation is as follows. If the information recording disk 103 revolves at low speed or stops, the microprocessor 104 instructs a revolving speed control means 107 to spin the disk at the maximum speed and a reader from information recording disk 108 to read information from the information recording disk 103. At this time, the revolving speed setting that the revolving speed control means 107 received as the instruction from the microprocessor is stored into a RAM 110. The revolving speed control means 107 comprises a spindle motor for spinning the information recording disk 103 and a control circuit for controlling the speed of the spindle motor.
When instructed to read, the reader from information recording disk 108 which is a means for reading object data starts reading the data from the information recording disk 103, no matter what speed at which the disk revolves. The reader from information recording disk 108 comprises an optical pickup for reproducing information from the information recording disk 103. The optical pickup is comprised of a semiconductor laser, optical components, a focus actuator, a tracking actuator, a light-sensitive detector, and other elements. Light emitted from the semiconductor laser converges on a focal point, thus making a light spot on the signal recording surface of the information recording disk 103. Because the quantity of light reflected from the light spot changes, depending on whether a pit exists on the disk surface, signal reproduction can be accomplished by detecting the changes in light quantity as signals.
The microprocessor 104 instructs a decoder 109 to decode the information read by the reader from information recording disk 108 into form in which the information can be transferred to the host computer 101. The decoder 109 executes decoding the read information, using a buffer 106. The microprocessor 104 also instructs the decoder 109 to transfer the information decoded by the decoder 109 (such as, e.g., information causing an interruption and a value contained in a register) to the host computer 101. The decoder 109, thus instructed, transfers the decoded information to the host computer 101.
If the microprocessor 104 remains not receiving a command to read information from the host computer 101 for a preset period, it instructs the revolving speed control means 107 to spin the disk at low speed. If the microprocessor 104 still remains not receiving a command to read information for a further longer preset period, it instructs the revolving speed control means 107 to stop the disk. Each time the disk revolving speed changes, the revolving speed setting recorded in the RAM 110 is updated. Next time the microprocessor is commanded to read information from the host computer 101, it instructs the revolving speed control means 107 to spin the disk at the maximum speed.
In the above-described CD-ROM drive or the like in accordance with prior art, the revolving speed control means 107 for reading information from the information recording disk 103 is instructed to spin the disk at full speed only as commanded to read information from the host processor 101. Whenever a read command is issued from the host computer 101, the revolving speed control means 107 is always instructed to spin the disk at the maximum speed. This results in consuming power more than required and generating unnecessary noise and vibration. Attention should be paid to address this drawback for data to be read or written from/onto a CD-ROM or any other randomly accessible disk, or for portable, mobile equipment such as notebook-size personal computers for which requirement of reduced power consumption is important.
While the foregoing description discussed the case where information is read from the information recording disk 103, in view of the disk revolving speed, the same problem arises when information is recorded onto the disk 103 as is the case for reading information from the disk.
In accordance with the present invention a device and method for transferring information with an information storage device includes operating the information storage device at one of a number of rotational speeds. Size information pertaining to the amount of data involved in the transfer is received and based on the received size information, the rotational speed of the information storage device is operated accordingly.